For cylinder identification, i.e., to detect the compression in one cylinder, for example, cylinder 1 of the engine, during one working cycle, the German Published Patent Application No. 34 31 232 has already disclosed providing two sensor wheels, the first sensor wheel turning at crankshaft speed and the second sensor wheel turning at half of the crankshaft speed, which is the speed of the camshaft. By synchronizing the signals generated in the sensors assigned to the sensor wheels, one is able to exactly identify which stroke of the combustion cycle the engine is in. With this method, when the sensor used to detect camshaft revolution fails, one can no longer identify the exact position of the piston of one cylinder during one combustion cycle because of the missing phase signal.